Genicom MatrixPrinter LA36 User Manual
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(2) RS-423 serial interface
The serial interface control circuit is basically the same as the Centronics circuit, except that it has a serial-
parallel converter. Serial data sent to the interface circuit input terminal is converted to TTL by the receiver IC
and applied to the MPU (MB90706), which converts serial data to parallel. The MPU recognizes that data has
been received and stores the information in the receive buffer or processes it immediately. The MPU may send
out buffer status information such as DC1/DC3 (buffer near empty or buffer full) from the serial interface output
terminal, depending on the selected protocol. It may also change the status such as DTR (ready to accept data)
under certain protocols.
DSR
RD
Transmitted data
TR
SD
Read data
ST D
0
D
1
D
2
D
3
D
4
D
5
D
6
D
7
SP
ST D
0
D
1
D
2
D
3
D
4
D
5
D
6
D
7
SP
Note:
If the signal line TR is open, the printer ignores control related to this signal.
Figure 5.24 RS-423 serial interface signal timing